1. Field of Invention
The invention relates to water-soluble pouches and more specifically to methods for packing chemical compositions in water-soluble pouches.
2. Description of Related Art
Water-soluble pouches are economical, easy to handle, and safe to use. Thus, they are becoming of interest for packaging and delivering liquid concentrates and powders. They provide many advantages for both the supplier and end-user and can be used with many different types of products, such as detergents, cleaners, degreasers, deodorizers, and pesticides. These pouches can also be used with hazardous materials to limit exposure of workers to toxins.
The preferred material used to make water-soluble pouches is polyvinyl alcohol (PVA) film. PVA is generally partially or fully alcoholyzed or hydrolyzed (e.g., 40-100%, preferably 80-99% alcoholyzed or hydrolyzed) and comes in many different varieties including biodegradable and edible films, cold and hot water-soluble films, and a number of different formulations to ensure compatibility with different products. Some examples of different PVA water-soluble pouches are described in several U.S. patents and applications, including U.S. Pat. No. 4,844,828, U.S. Pat. No. 4,340,491, U.S. Pat. No. 5,222,595, and U.S. Patent Publication 2003/0100463. Other suitable materials include polyethylene oxide, such as polyethylene glycol; starch and modified starch; alkyl and hydroxyalkylcellulose, such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropyl cellulose; carboxymethylcellulose; polyvinylethers such as poly methyl vinylether or poly(2-methoxyethoxyethylene); poly(2,4-dimethyl-6-triazinylethylene; poly(3-morpholinyl ethylene); poly(N-1,2,4-triazolylethylene); poly(vinylsulfonic acid); polyanhydrides; low molecular weight melamine-formaldehyde resins; low molecular weight urea-formaldehyde resins; poly(2-hydroxyethyl methacrylate); polyacrylic acid and its homologs. Polyvinyl acetate (or other ester) film, copolymers or other derivatives of such polymers can also be used.
There are two popular methods of packaging items in water-soluble pouches: vertical form/fill/seal (VFFS) and horizontal form/fill/seal (HFFS). In the VFFS process, a packaging machine transports the PVA film vertically downward and forms a tube. Next, the machine fills the tube with the desired product and the tube is sealed. Accordingly, the VFFS process is the preferred method for packaging items in a liquid, powder, paste or granular state. The HFFS process operates similarly. A packaging machine transports the PVA film in a horizontal direction and then forms a pouch. The machine fills the pouch with the desired product and seals it. Consequently, this process is widely used for packaging solid items. The two processes enable water-soluble pouches to be used for a variety of applications.
The use of water-soluble pouches provides a number of benefits. One is the reduced shipping cost of products. Because the pouch contents are in a concentrate or powder form, suppliers do not have to ship a solution containing a large amount of water, thus reducing shipping weight. In addition, the size of packaging is decreased, thereby reducing shipping costs even more. Likewise, the reduced package size minimizes storage costs for both the supplier and end-user.
Furthermore, water-soluble pouches are convenient and safe for everyone involved in the transport and use of chemical compounds. The pouches are suitable for hazardous solutions such as pesticides or herbicides. Therefore, workers and end-users are not exposed to hazardous materials or dust while handling the compositions or mixing them into the final solution. In addition, because these pouches contain a pre-measured amount of concentrate or powder, the end-user mixes the entire pouch in a specified amount of water to make a desired amount of solution. Thus, no product loss or exposure is involved in the process of dissolving the contents into a functional container such as a spray bottle or canister.
Despite the benefits of water-soluble pouches, there are some disadvantages. Because it is convenient for the pouches to dissolve in water rapidly, the PVA material is used in thin films which are necessarily flexible and flimsy. Therefore, it is difficult to insert the pouches in containers with small openings through which they need to be manipulated. This can cause the pouch to burst spilling the contents, possibly exposing the user to dangerous chemicals.
Therefore, there is a need to improve water-soluble pouches to limit the flexibility of the package so as to facilitate the process of introducing the pouches through bottle necks and reducing the risk of the pouch rupturing.